1. Field of the Invention
The invention is concerned with fuel priming pumps for internal combustion engines. Such fuel priming pumps are normally associated with check valves mounted in external hardware such as an adapting bracket or the like. Such pumps give rise to installation, servicing and related problems due to their somewhat complex construction. In addition, a number of conventional priming pumps are prone to leakage and exhibit an inability to be worked easily. The present invention is most particularly concerned with an improvement in a fuel priming pump which assures that the fuel being pumped cannot pass around the plunger which pumps it and thereby wet the hand of the person doing the pumping thereby presenting a serious safety problem.
2. Prior Art
Fuel priming pumps are of course well known to the prior art. One particularly useful pump in this regard is disclosed in U.S. Pat. No. 3,669,576. The pump disclosed in this patent has a plunger which is screw-threadable to a flange which fits over external hardware, with check valves being included in the flange. The pump of this patent further discloses a particular low friction seal between the periphery of the plunger and the inside of a barrel within which the plunger reciprocates. U.S. Pat. No. 3,500,759 discloses yet another fuel priming pump. This pump when not in use is fastened with its piston reciprocated into its barrel via a pivoted spring lock arrangement.
With the prior art fuel priming pumps a particular problem exists, namely the problem of fuel escape around the plunger and up into the barrel of the pump above the plunger. This problem arises due to fuel at high applied pressure which may be trapped in the chamber between the plunger and the inlet and outlet check valves. In particularly, after the pump has been used the plunger must be slid downwardly and secured to the base. In doing so, the pressure of fuel normally filling or flowing through the chambers below the plunger is substantially increased by downward movement of the plunger. Such increased pressure can result in leakage past the plunger seal means and it eventually enters the upper dry chamber. From the upper chamber pumping action tends to detrimentally expel the fuel past the handle of the pump. Also, when the plunger is fastened in its innerwardly reciprocated position fuel is trapped between the bottom of the plunger and the flange thus creating a hydraulic lock which again focres fuel to escape past the plunger itself and up into the barrel above the plunger. When this happens, fuel trapped between the plunger and the chamber formed by the barrel portion of the pump squirts out when the pump handle is pulled up preparatory to using the pump again. The amount of fuel leaked out, while small, is sufficient to wet an individual's hand, damage clothing and the like and create potential fire hazards.
It is thus highly desirable to provide an improvement in fuel priming pumps which solves the problem of fuel escaping about the plunger and collecting in the chamber between the plunger and the handle of the pump thereby creating fire hazards. The provision of a positive acting, yet quick to engage and disengage system for locking the plunger within the barrel reciprocated towards the check valves therein would likewise be desirable so that the pump could readily be used and/or locked in place. The present invention is concerned with a unique and unobvious solution to the above set out problems.